The Liberal Party has escaped a voter backlash in Saturday's two federal by-elections, despite the recent leadership turmoil and divisions over climate change policy.

There were celebrations as the Liberal party retained its hold on the safe Liberal seats of Bradfield and Higgins in Sydney and Melbourne.

The Liberal candidate in Bradfield, Paul Fletcher, celebrated victory with a result that left the party's margin virtually intact.

He says the issue of climate change did not damage the party.

"Climate change was coming up as an issue, but it wasn't the number one issue," he said.

It was the same in Higgins, where the Liberals' Kelly O'Dwyer retained the seat previously held by her mentor, former treasurer Peter Costello.

She said Labor's absence from the contest did not necessarily translate as votes for the Greens.

"I think it sends a clear message to Kevin Rudd that they cannot take their voters for granted," she said.

"Their voters will come to the Liberal Party if given an opportunity."

There was a smaller than expected swing of just 0.6 per cent against the Liberal Party, and Ms O'Dwyer says that is a clear endorsement of the new Liberal leader, Tony Abbott.

"It's also a very good win when you consider it's been a very tough fought campaign," she said.

She says Labor's "gutless" decision not to run a candidate means voters didn't have the chance to hold the Government to account.

"The Rudd Government at the last election promised that they would be responsible economic managers, they promised that they would be economic conservatives, yet they've done what every Labor government to date has always done, which is plunged the country back into debt," she said.

The ABC's election analyst Antony Green says it is a solid performance.

"The Liberal Party has managed to retain its hold on both seats," he said.

"They've kept their record intact of never having gone to preferences in either seat."

Greens fail to dent Liberal margin

The Greens say the issue of climate change did influence voters but the Liberals maintain it had no real impact on the outcome.

The Greens increased the party's primary vote in both seats in the absence of a Labor candidate, but made no dent on the Liberal party's margin.

The Greens' candidate for Higgins, academic Clive Hamilton, increased his party's primary vote, but failed to take many voters away from the Liberal Party.

He says it was a good outcome for the Greens.

"The Greens have achieved a vote of 35 per cent or so, which is easily the highest vote the Greens have scored in a House of Representatives election," he said.

"That means about a quarter of the voters of Higgins who once voted Labor or Liberal have decided to trust their vote to the Greens."

Dr Hamilton says Ms O'Dwyer will toe the party line on climate change.

She says she is not a climate change sceptic, but doesn't support the emissions trading scheme in its current form.

"I support effective action on climate change," she said.

"The ETS that was brought forward by the Rudd Government was an ETS that a lot of Higgins voters said they had concerns about, they weren't sure what it was going to cost, they weren't sure it was actually going to be effective and they wanted to know why they were going to be rushed into making a decision."